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Thread: Cloudy Tenax-7R

  1. Default Cloudy Tenax-7R

    Hello! After a too-long hiatus from the workbench, I picked up on an "old" project I'd started, working with styrene. I noticed that my bottle of Tenax-7R has turned "cloudy". Does this mean that it is "no good" or of limited use, or can I continue using it?

    While looking through my stash for something else to use, I found an unopened bottle of Tenax, still crystal-clear. I will assume that it IS still good... but I don't want to open it unless I "have to", because something has affected the clarity (and possibly the useability?) my old bottle of Tenax.

    If I understand correctly, Tenax is no long available on the market -- a chemical used in it has been banned? If that is the case, does anyone have a recommendation for another clear, fast-drying, thin cement for use on styrene?

    Thanks in advance for your comments!

    Regards,
    Tom Stockton
    "If I only had a train!"

  2. #2
    Join Date
    Aug 2016
    Location
    Central Minnesota, Park Rapids area.
    Posts
    1,127

    Default

    Try the cloudy stuff and see if it works. If not; or, the cloudiness easily shows in the joint, your choice, whether to use or not. Since you have second bottle, try it to see if it works, again, your choice as to using it; or, not. There are many, many other choices for plastic cement. Testors (My personal choice) Plaststruct Plastic Weld, Various Cynoaccrylate CA Glues. Faller even makes a plastic cement. The choices are many. Take a look here: http://www.modeltrainstuff.com/Glues...show=30&page=1

    Walthers still lists Tenax 7R as a product they sell. However, they list it as out of stock at this time. Some of the other boards are talking about TENAX 7R being a "Gonner". Looks to me like you should hold onto your clear bottle of the product and wait for the price to "Sky Rocket", then sell it off, grab the huge profit and take the wife on that European vacation you've talked about!

    I come from a time when the only choice you had was Testors in the tube; or, Testors in the bottle with the brush. I've found that the bottle with the brush is the best way to apply plastic cement (albeit with most of the bristles cut off). Now, Testors no longer offers the bottle with brush, as they've come out with an applicator with the glue, that costs about $7.50 at my closest hobby shop, when the old bottle with the brush only cost less than $2.50.

    Ahh, ain't Progress Wonderful!!
    Last edited by NP2626; 02-16-2017 at 05:01 AM.
    Mark D.

    Opinions given are my own and not meant to ruffle any feathers.
    Northern Pacific, really terrific!

  3. #3

    Default

    Not to worry, the are no banned chemicals in Tenax-7R. Tenax is a huge adhesives manufacturer. They just dropped the hobby products from their line. Any of the plastic "welds" will serve. They are all some combination of Methyl Ethyl Ketone, Acetone, and/or Toulene. Cloudy typically means water contamination. Shouldn't hurt the function, but it might slow the setting time. As Mark said, test it on some scrap.
    Kevin

    General Manager
    Red Oak and Western Railway Company

  4. Default

    Here are some pretty good discussions on those various plastic 'glues'
    http://model-railroad-hobbyist.com/node/8083

    I've used Tenax 7R in the past on a number of projects and really like the way it would bond things together without any residue or shiny appearances. But it does evaporate readily even out of tightly cover jars. Its nice to know that MEK is basically what Tenax is.

    One of those postings also had a very good 'application suggestion,...I used this very successfully
    I've used MEK as a cement on styrene plastic structure kits with good success. I bought 1 qt. cans of it at my local Lowes store for about $9.00. Since very little needs to be used to accomplish the task, a quart of MEK will last you along time.

    As stated above you should take precautions with MEK, i.e., avoid skin contact and breathing it.

    Since very little is necessary to stick two pieces of styrene together, I would suggest that you consider using the Touch-N-Flow Applicator sold by Micro-Mark, Item #81778 at $7.60. This applicator consists of a glass capillary tube with a very fine steel needle at its tip. All you have to do is touch the steel tip to the joint you want to glue and the MEK will flow out of the applicator into the joint by capillary action. This reduces the chance of exposure to the liquid or vapor.
    Last edited by beiland; 02-18-2017 at 08:48 PM.

  5. Default

    Yes, try it and see if it works. I only use the stuff on areas that aren't visible anyway so the only thing that matters is if you get a good bond or not.

    I've got an old bottle of the stuff and it still seems to work great. When it runs out I'll have to fine a suitable replacement - others have already suggested other weld adhesives.

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